Field of the Invention
The present invention relates to a manufacturing method of a rotating electric machine and more particularly to a manufacturing method of a rotating electric machine whereby to manufacture the rotating electric machine by twisting and bending the end portions of conductors.
Description of the Related Art
Hitherto, there has been proposed an apparatus that twists and bends the end portions of conductors (coil segments) projecting from slots formed to be arranged in the circumferential direction of a stator core. For example, Japanese Patent Application Laid-Open No. 2001-197709 (hereinafter referred to as Patent Document 1) describes a method wherein, in a state in which a plurality of conductors project from the slots of a stator core and arranged in the radial direction of the stator core such that the conductors form a plurality of layers, the end portion of each conductor are held and the conductors are twisted and bent while moving the end portions in the circumferential direction. In the method, annular jigs (guides) corresponding to the conductors of respective layers are used.
Whenever the conductor end portions are moved in the circumferential direction, the conductor end portions inevitably shift also in an axial direction. Therefore, in order to twist and bend the conductors, it is necessary to shift the conductor end portions in the circumferential direction and the axial direction. According to the method described in the foregoing Patent Document 1, the annular jig that sandwiches both side surfaces of the conductor end portions of each layer to hold the conductor end portions is rotated in the circumferential direction and at the same time, the annular jig is moved also in the axial direction independently for each layer according to the movement distance of the conductor end portions in the axial direction.
To improve the performance, including the magnetic flux density, of the rotating electric machine, the twisted and bent conductor end portions of the layers preferably have the same height. However, if the conductor end portions are moved in the circumferential direction by the same angle, then the conductors on a radially outer side and the conductors on a radially inner side will have different movement distances in the circumferential direction, inevitably causing the conductor end portions to have different movement distances also in the axial direction. Hence, according to, for example, the method described in the foregoing Patent Document 1, the projecting lengths of the conductor end portions before being twisted and bent are set to be longer for the layers in farther radially outer side, and radially outer jigs and radially inner jigs are rotated in the circumferential direction by the same angle.
To change the projecting lengths of the conductor end portions before being twisted and bent for each layer as described above, it is required to prepare a plurality of types of conductors having different lengths as the materials and to arrange the conductors for each layer in order and dispose the conductors in slots. This poses a problem in that the preparatory process for twisting and bending the conductors becomes complicated, resulting in deteriorated production efficiency.